Unitary energy absorbing assembly and method of making the same

ABSTRACT

An energy absorbing assembly can comprise: a support structure having a first wall and an outer wall that extend in an x direction from a first end to a second end; an energy absorber that extends across the first wall of the support structure, the energy absorber comprising a plurality of crushable members are configured to crush and absorb energy upon impact, a first crash can; and a second crash can, wherein the first and second crash cans extend from the first and second ends of the support structure. The energy absorbing assembly is an in situ formed single element. A method of making an energy absorbing assembly can comprise: introducing molten thermoplastic material to a mold to in situ form the energy absorbing assembly and removing the energy absorbing assembly from the mold by moving the mold in a y direction.

BACKGROUND

The present disclosure relates generally to energy absorbers for use ina vehicle, for example, to reduce injuries (e.g., to occupant(s),pedestrian(s), etc.) and/or to reduce vehicle damage.

Bumper systems generally extend widthwise, or transverse, across thefront and rear of a vehicle and are mounted to rails that extend in alengthwise direction. Many bumper assemblies for an automotive vehicleinclude a metal bumper beam and an injection molded energy absorbersecured to the bumper beam. The bumper system generally further includesan energy absorber along the surface of the bumper and also a fascia forcovering the energy absorber.

Beneficial energy absorbing bumper systems achieve high efficiency bybuilding load quickly to just under the load limit of the rails andmaintain that load constant until the impact energy has been dissipated.Energy absorbing systems attempt to reduce vehicle damage and/or injuryas a result of a collision by managing impact energy absorption. Bumpersystem impact requirements are set forth by United States Federal MotorVehicle Safety Standards (US FMVSS), Canadian Motor Vehicle SafetyStandards (CMVSS), European EC E42 consumer legislation, EuroNCAPpedestrian protection requirements, Allianz impact requirements, andAsian Pedestrian Protection for lower and upper legs. In addition, theInsurance Institute for Higher Safety (IIHS) has developed differentbarrier test protocols on both front and rear bumper systems. Theserequirements must be met for the various design criteria set forth foreach of the various automotive platforms and car models. If there iseven very limited damage to any component of the frame of the vehicle,costs of repairing the vehicle can escalate dramatically.

This generates the need to develop low cost, lightweight, and highperformance energy absorbing systems that will deform and absorb impactenergy to ensure a good vehicle safety rating, absorb energy upon impactwith a pedestrian to reduce the injuries suffered by the pedestrian, andreduce vehicle damage in low speed collisions, e.g., to inhibit framedamage. Different components due to their inherent geometry and assemblyrequirements need different energy absorber designs to satisfy theimpact criteria. Therefore, the automotive industry is continuallyseeking economic solutions to improve the overall safety rating of avehicle. Hence, there is a continual need to provide a solution thatwould reduce injuries and/or reduce vehicle damage and/or enhance avehicle safety rating.

BRIEF DESCRIPTION

Disclosed, in various embodiments, are energy absorbing devices andmethods of making energy absorbing devices that can be used inconjunction with various vehicle components.

In an embodiment, an energy absorbing assembly can comprise: a supportstructure having a first wall and an outer wall that extend in an xdirection from a first end to a second end; an energy absorber thatextends across the first wall of the support structure, the energyabsorber comprising a plurality of crushable members are configured tocrush and absorb energy upon impact, a first crash can; and a secondcrash can, wherein the first and second crash cans extend from the firstand second ends of the support structure. The energy absorbing assemblyis an in situ formed single element.

In one embodiment a vehicle comprises a body and rails and an energyabsorbing assembly. The energy absorbing assembly comprises a supportstructure having a first wall and an outer wall that extend in an xdirection from a first end to a second end; an energy absorber thatextends across the first wall of the support structure, the energyabsorber comprising a plurality of crushable members are configured tocrush and absorb energy upon impact, a first crash can; and a secondcrash can, wherein the first and second crash cans extend from the firstand second ends of the support structure and wherein the first andsecond crash cans attach to the rails without a bumper beam. The energyabsorbing assembly is an in situ formed single element.

In one embodiment, a method of making an energy absorbing assembly cancomprise: introducing molten thermoplastic material to a mold to, insitu form the energy absorbing assembly comprising a support structure,energy absorber, first crash can, and second crash can, wherein thesupport structure has a first wall and an outer wall having ends,wherein the first and second crash cans extend from the ends of thesupport structure, and the energy absorber extends across the first wallof the support structure; and removing the energy absorbing assemblyfrom the mold by moving the mold in a y direction.

These and other non-limiting characteristics are more particularlydescribed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings wherein likeelements are numbered alike and which are presented for the purposes ofillustrating the exemplary embodiments disclosed herein and not for thepurposes of limiting the same.

FIG. 1 is an isometric view of an energy absorbing assembly comprising abumper beam, an energy absorber, and crash cans.

FIG. 2 is an isometric view of a bumper beam.

FIG. 3 is an isometric view of a bumper beam.

FIG. 4 is an isometric view of a portion of an energy absorber.

FIG. 5 is an isometric view of a portion of an energy absorber.

FIG. 6 is a back isometric view of a crush box.

FIG. 7 is a front isometric view of a crush box.

FIG. 8 is an isometric view of an energy absorbing assembly comprising abumper beam, energy absorber, and crash cans.

FIG. 9 is a cross-section side view of the energy absorbing assembly ofFIG. 8 taken along line A-A.

FIG. 10 is a graph illustrating acceleration versus time for pedestrianlower leg impact testing.

FIG. 11 is a graph illustrating rotation versus time for pedestrianlower leg impact testing.

FIG. 12 is a graph illustrating shear versus time for pedestrian lowerleg impact testing.

FIG. 13 is a graph illustrating the force observed in center pendulumtesting.

FIG. 14 is a graph illustrating the back of the beam displacement versustime observed in center pendulum testing.

FIG. 15 is a graph illustrating the amount of energy absorbed versustime for vehicle damageability results.

FIG. 16 is a graph illustrating the force versus time for vehicledamageability results.

DETAILED DESCRIPTION

Disclosed herein, in various embodiments, are energy-absorbingassemblies which can be used in conjunction with vehicle components,e.g., to minimize the damage and/or injury suffered during an impact.The energy absorbing assembly can comprise a support structure, anenergy absorber (e.g., crush lobes), and crash cans, each of whichcomprise a plastic material, and all of which are formed in situ as asingular, solitary component. The energy absorbing assemblies eliminatethe metal bumper beam and comprise an integrated assembly of athermoplastic support structure extending between plastic crash cans,with a plastic energy absorber along a side of the support structure.The crash cans are configured to protect the vehicle rails, e.g., forimpacts of greater than or equal to 15 km/hr. The crash cans can absorbimpact energies of 3,000 Joules, in some embodiments, impact energies of4,000 Joules, specifically, impact energies of 6,000 Joules, and evenimpact energies of 10,000 Joules. The plastic energy absorber comprisescrush lobes configured to aid in pedestrian protection (e.g., for lowerleg impacts less than or equal to 40 kilometers per hour (km/hr) (suchas impacts of 30-40 km/hr). The energy absorber can absorb impact energyof 450 Joules, and in some embodiments, impact energies of 850 Joules,specifically, impact energies of 1,000 Joules.

The support structure, crash cans, and crush lobes are formed in situ,e.g., using a vertically moving mold (i.e., in the y direction). In someembodiments, the assembly has no outermost wall extending in the x and zdirections covering the energy absorber, covering the support structure,and/or covering the crash cans (e.g., the outermost surfaces in the ydirection on both sides of the assembly). The assembly can haveoutermost walls extending in the x and y directions on one or both sidesof the assembly, over the support structure (e.g., first wall 18 andthird wall 22 of FIG. 1), over the energy absorber (e.g., front wall 26of FIG. 1), and/or over the crash cans (e.g., front face 50 and backface 52 of FIGS. 6 and 7).

In various embodiments, the crash cans form the ends of the assemblywith the thermoplastic support structure extending between the crashcans. In front of the support structure and crash cans are the energyabsorbers (e.g., crush lobes), extending across the assembly, across thecrash cans and support structure. The crash cans can attach to the bodyin white (BIW), e.g., to the projecting supports (e.g., vehicle rails).A redesign was needed in order to attain this design, i.e., a unitaryabsorbing assembly that replaces separate elements of the metal bumperbeam, energy absorbers, and crash cans. The various embodiments areformed with openings in the y direction (see FIG. 1).

The integrated assembly provides a significant reduction in the weightof the overall assembly (e.g., up to a third weight reduction comparedto assemblies comprising a metal bumper beam and/or metal crash cansthat meets the same energy absorption capacity) since each componentcomprises a thermoplastic material, while simultaneously providing highperformance (e.g., controlled crushing and hence an increase inefficiency compared to metal energy absorbers) during pedestrian impactsand also during low speed collisions. Because of the integratedassembly, the energy absorbing assemblies described herein can replacemetallic bumper beams and/or crash cans. The result is a reduction intime required to assemble the components and hence, a decrease in theoverall cost of the assembly. The energy absorbing assembly can bemanufactured utilizing various molding processes (e.g., injectionmolding, thermoforming, extrusion, etc.) to provide a single pieceassembly (e.g., an integrally formed support structure, energy absorber,and crash can).

Although the energy absorbing assemblies disclosed herein can be used inany location in a vehicle, the energy absorbing assemblies are intendedto be located at the front portion of a vehicle (e.g., in the portion ofthe vehicle where the engine, radiator, etc. are generally located) toprotect the body in white (BIW) and components located behind the BIWfrom damage when an impact occurs. Generally, the energy absorbingassembly can be located in front of and attached to the BIW to serve asprotection to the structure during an impact. For example, the energyabsorbing assembly can be attached to the vehicle rails and/or crossmembers located on the BIW. The energy-absorbing component of theassembly can be located in front of the support structure to reduce theinjury to a pedestrian upon impact. Crash cans assist in supporting thesupport structure at opposing ends (e.g., at the left end and the rightend of the support structure (the support structure can have a lengththat is less than the distance between the vehicle rails)). The crashcans provide stiffness to protect the vehicle rails from damage after animpact. Crash cans also generally serve the function of reducing vehicledamage and driver/occupant injury during an impact. This solution isobserved to be greater than or equal to 20% lighter than the priordesigns while achieving the same performance, e.g., than the designdisclosed in U.S. Pat. No. 7,044,515.

Metal bumper beams and crash cans are generally heavy in weight and areexpensive to manufacture. Also, metal bumper beams cannot be formedintegrally (e.g., in situ) with plastic energy absorbers or plasticcrash cans, thus increasing the processing time with an energy absorbingassembly that comprises metal bumper beams and/or metal crash cans.Additionally, since metal bumper beams are not formed integrally withthe energy absorber and crash cans, additional assembly time isnecessary with metal bumper beams, which also increases the overall costof an energy absorbing assembly utilizing a metal bumper beam. The sameissues are true with metal crash cans, i.e., metal crash cans cannot beformed integrally with the metal bumper and/or plastic energy absorber,increasing both processing and assembly times for the energy absorbingassemblies. Automotive manufacturers continually desire lighter weight,highly efficient, cost effective solutions for such components of anautomobile. By providing a single piece assembly where each component ofthe assembly comprises a thermoplastic material, significant savings inweight, processing times, and assembly times can be achieved. Forexample, up to a one-third reduction in weight can be observed whereeach component of the assembly comprises a thermoplastic material.Decreased assembly times can also be achieved with a single pieceassembly. For example, the assembly time can be decreased by at least35%.

The energy absorbing component (e.g., crush lobes) of the assembly canbe designed to absorb energy and deform during impact with a pedestrian,the support structure can be designed to provide support to the energyabsorber and serve as a stiff member that elastically deforms andabsorbs energy during pendulum and barrier impacts, while the crash canscan be designed to plastically deform and absorb energy during Allianzimpact and/or for RCAR and also can provide support for the plasticbeam. In other words, the support structure has a stiffness that isbetween the stiffness of the crash cans and the energy absorber (e.g.,crush lobes). Allianz impact refers to a test where the front of avehicle is driven against a rigid barrier at an angle of 10 degrees tothe vehicle movement direction with an overlap of 40% on the driver'sside, while RCAR refers to an impact at 15 kilometers per hour (km/hr).Pendulum and barrier impact test refer to FMVSS 581.1-581.7 at avariable speeds. Pendulum impact speed is 1.5 mile per hour (mph) forthe corner impact on a vehicle at 30 degrees to the vehicle movementdirection and 2.5 mph for all other pendulum and barrier impacts whichare in the same direction as that of the vehicle movement direction.

The energy absorbing assemblies described herein are capable of meetingand/or exceeding requirements set forth for low speed crashes, e.g.,ECE-42 and RCAR/Allianz/Danner/Thatcham Impacts, as well as meetingand/or exceeding pedestrian impact regulatory requirements, e.g., EEVC,ACEA (Phase II), and GTR. EEVC Working Group 17 and ACEA (Phase II)correspond to pedestrian impact requirements, the latter being morestringent. They have also developed the test procedures and quantifiedthe maximum permissible damage to a pedestrian leg dummy model when itis impacted by an automobile, so that the pedestrian will be safe duringthe impact.

Exemplary characteristics of the energy absorbing assembly include hightoughness/ductility, thermal stability, high energy absorption capacity,a good modulus-to-elongation ratio, and recyclability, among others,wherein “high” and “good” are intended to mean that the characteristicat least meets vehicle safety regulations and requirements for the givencomponent/element. The support structure, energy absorber, and crashcans individually comprise the same or different plastic material (e.g.,thermoplastic material). The support structure, energy absorber, and/orcrash can can comprise any thermoplastic material or combination ofthermoplastic materials that can be formed into the desired shape andprovide the desired properties. Desirable modulus values for thematerials can be greater than or equal to 0.6 gigaPascals (GPa),specifically 0.6 GPa to 20 GPa, more specifically 3 GPa to 20 GPa. Forefficient energy absorption, it is desirable that the material has highvalue of strain to failure typically 20% to 130%, specifically 30% to120%, and more specifically, 80% to 110%.

Exemplary materials include thermoplastic materials as well ascombinations of thermoplastic materials with elastomeric materials,thermoset materials, metals, and/or composites, such as plastic-metalhybrid structures and/or plastic-composite hybrid structures. Possiblethermoplastic materials include polybutylene terephthalate (PBT);acrylonitrile-butadiene-styrene (ABS); polycarbonate; polycarbonate/PBTblends; polycarbonate/ABS blends; copolycarbonate-polyesters;acrylic-styrene-acrylonitrile (ASA);acrylonitrile-(ethylene-polypropylene diamine modified)-styrene (AES);phenylene ether resins; blends of polyphenylene ether/polyamide;polyamides; phenylene sulfide resins; polyvinyl chloride PVC; highimpact polystyrene (HIPS); low/high density polyethylene (L/HDPE);polypropylene (PP); expanded polypropylene (EPP); and thermoplasticolefins (TPO). For example, the support structure, energy absorber,and/or crash can comprise Xenoy® plastic resin, which is commerciallyavailable from SABIC Innovative Plastics IP B.V. The support structure,energy absorber, and/or crash cans can also be formed from combinationscomprising at least one of any of the above-described materials.

The overall size, e.g., the specific dimensions of the energy absorbingassembly will depend upon its location in the vehicle and its function,as well as the particular vehicle for which it is intended. For example,the length (l), height (h), and width (w) of the energy absorbingassembly, will depend upon the amount of space available in the desiredlocation of use as well as the needed energy absorption. The depth andwall thicknesses of the support structure, energy absorber, and/or crashcans will also depend upon the available space, desired stiffness, andthe materials (or combination of materials) employed. For example, thewidth, w, of the energy absorber can be less than or equal to 200millimeters mm, specifically, 50 mm to 200 mm, and more specifically 80mm to 90 mm. The height, h, of the support structure can be less than orequal to 250 mm, specifically, 50 mm to 150 mm, and more specifically 70mm to 80 mm. The energy absorber (e.g., crush lobes) can extend thelength of the support structure, specifically, the crush lobes canextend across the length of the support structure and the crash canscombined, e.g., to provide energy absorption across the assembly.

The thickness of the walls of the support structure, energy absorber,and/or crash cans can all be the same or can be different to enhancestiffness in a desired direction. For example, the crash cans can havethicker walls at the front than at the back, e.g., the surface facingthe BIW, the energy absorber can have thicker walls in the middle ortoward one or both ends of the energy absorber, and the supportstructure can have thicker walls toward the ends where the crash cansare located.

The energy absorbing assembly can be produced by several methods such asmolding (e.g., injection molding, injection compression molding),forming, extrusion, and/or any other suitable manufacturing technique.For example, the support structure, energy absorber, and crash cans canbe formed by a process such as injection molding, thermoforming,extrusion, and combinations comprising at least one of the foregoing. Invarious embodiments, order to attain the desired energy absorption andenable the in situ formation of the assembly, a process that utilizesmolds that move in the y-direction (see FIG. 1), such that the assemblycomprises openings, e.g., on both sides thereof, in the y direction,with the energy absorbers and support structure are closed in the x andz directions (e.g., have external walls in the x and z directions suchthat no opening or cavity is formed in those directions, but hasopenings such that cavities and/or channels are formed in the ydirection). (See FIGS. 1-8) The crush lobes can be open in the ydirection (e.g., between vertical walls 56 and ribs 54) and optionallyhave an opening in the x direction (e.g., hollow portion 58 of FIG. 6).

The energy absorbing assembly is designed so as to have greaterstiffness in the crash cans than the support structure to absorbsignificantly higher amount of energy during RCAR/Allianz 15 km/hroutboard impact cases, and greater stiffness in the support structurethan in the energy absorber (e.g., crush lobes) so that the supportingstructure is stiff enough to provide adequate reaction to the energyabsorber for crushing during lower leg impact case. For example, if thesupport structure stiffness is “SS”, the crash cans can have a stiffnessof 2 SS to 5 SS, specifically, 2.5 SS to 4.5 SS. The crush lobes canhave a stiffness of 0.2 SS to 0.9 SS, specifically 0.3 SS to 0.7 SS.

A more complete understanding of the components, processes, andapparatuses disclosed herein can be obtained by reference to theaccompanying drawings. These figures (also referred to herein as “FIG.”)are merely schematic representations based on convenience and the easeof demonstrating the present disclosure, and are, therefore, notintended to indicate relative size and dimensions of the devices orcomponents thereof and/or to define or limit the scope of the exemplaryembodiments. Although specific terms are used in the followingdescription for the sake of clarity, these terms are intended to referonly to the particular structure of the embodiments selected forillustration in the drawings, and are not intended to define or limitthe scope of the disclosure. In the drawings and the followingdescription below, it is to be understood that like numeric designationsrefer to components of like function.

FIG. 1 illustrates energy absorbing assembly 10 comprising a supportstructure 12, an energy absorber 14, and crash can(s) 16. As illustratedin FIG. 2, the support structure 12 comprises a first wall 18 and asecond wall 20, and, optionally, a third wall 22. Ribs 24 can bedisposed between the first wall 18 and the second wall 20. Asillustrated in FIGS. 2 and 3, the ribs 24 can form triangular structuresextending across the length of the support structure 12. Ribs 24increase the stiffness and thus also the energy absorbing capabilitiesof the support structure so that less damage to the vehicle componentslocated behind the support structure occurs after a collision. Inembodiments where the third wall 22 is present, ribs 24 can also bedisposed between the second wall 20 and the fifth wall 22 as displayedin FIG. 3. In one embodiment as illustrated in FIG. 3, horizontallayer(s) 30 separates the first wall 18 and the second wall 20 of thesupport structure into a structure having an upper portion 32 and alower portion 34 where the ribs 24 are disposed in the upper portion 32and in the lower portion 34 between the first wall 18 and the secondwall 20. In embodiments where the third wall 22 is present, a horizontallayer 30 can divide the space between the second wall 20 and the thirdwall 22 into upper portion 32 and lower portion 34 as displayed in FIG.3. The presence of the third wall 22 with ribs disposed between thesecond wall 20 and the third wall 22 further increases the stiffness ofthe support structure 12, allowing the beam to absorb more energy uponan impact and further decreases the amount of damage suffered to thevehicle components located behind the support structure 12.

The support structure 12 can be designed such that the first wall 18,second wall 20, and optional third wall 22 each comprise openings 36 inthe direction of the y-axis as shown in FIG. 1 (i.e., the first wall 18,second wall 20, and option third wall 22 can be open on the top andbottom portions of the support structure). The ribs 24 can also besimilarly designed to have an opening 36 on the top and on the bottomportions on the support structure (i.e., opening 36 extends in thedirection of the y-axis). Such a design can allow for vertical moldmovement to occur during processing of the energy absorbing assembly 10as opposed to horizontal mold movement which generally allows for only asingle opening in the direction of the x-axis.

The support structure 12 generally comprises at least one row of ribs 24extending across the length of the support structure 12. In otherembodiments, the support structure 12 can comprise greater than one rowof ribs 24. For example, the support structure 12 can comprise greaterthan or equal to 2 rows of ribs, specifically, greater than or equal to3 rows of ribs, more specifically, greater than or equal to 4 rows ofribs, and even more specifically, greater than or equal to 5 rows ofribs. The ribs 24 can comprise any shape that will provide the desiredstiffness to the support structure 12 to enable it to absorb energy andprotect the vehicle components located behind the support structure 12from damage. The ribs 24 can comprise a shape such as triangular, truss,saw tooth, sinusoidal, lamellar, abs(sin), cycloid, and combinationscomprising at least one of the foregoing. The ribs 24 can aid inproviding and/or maintaining the connectivity of the support structure12 to the crash cans 16. In an exemplary embodiment, the ribs 24 can beconnected directly to the crash cans 16. In another embodiment, wherethe support structure 12 comprises side walls (e.g., a fourth wall and afifth wall, not illustrated) on either end of the support structure, thecrash cans 16 can attach to the side walls.

It is also contemplated that, depending on the desired stiffness, thenumber of vertical walls (e.g., first wall 18, second wall 20, thirdwall 22, etc.) and/or horizontal walls 30 present on the supportstructure 12 with ribs disposed between at least two of the verticalwalls can be increased or decreased. The vertical walls and thehorizontal walls are capable of providing the desired stiffness duringimpact. In one embodiment, as illustrated in FIG. 2, no horizontal layer30 is present and only one layer of ribs 24 is disposed between thefirst wall 18 and the second wall 20, while FIG. 3 illustrates anembodiment where two layers of ribs 24 are present, i.e., between thefirst wall 18 and the second wall 20 and between the second wall 20 andthe third wall 22 and two horizontal layers 30 are present, i.e., onehorizontal wall 30 located between first wall 18 and second wall 20 andanother horizontal wall 30 located between second wall 20 and third wall22. In another embodiment, greater than or equal to two layers of ribscan present with no horizontal layers. This is similar to the embodimentillustrated in FIG. 2, but at least one additional vertical wall withribs disposed therebetween are present. This embodiment can be usefulfor applications where less impact strength is desired (e.g., forsmaller cars). Additionally, without the presence of a horizontal layer30, the support structure 12 can be extruded providing a simple and costeffective method of manufacturing the support structure 12. The supportstructure 12 can also optionally comprise two vertical walls (e.g.,first wall 18 and second wall 20) and a horizontal wall 30 whichseparates the support structure into an upper portion 32 comprising ribs24 and a lower portion 34 also comprising ribs 24.

For small, compact cars, where the packaging space is generally lessthan in a larger vehicle, only a single layer of ribs (e.g., a firstwall and a second wall with ribs disposed therebetween as illustrated inFIG. 2) could be desired. For larger cars which have increased packagingspace a greater number of walls with ribs disposed therebetween could bedesired to achieve the desired stiffness of the support structure 12.The number of horizontal layers 30 could also be varied depending on thedesired stiffness of the support structure, with an increased number ofhorizontal layers 30 present when increased stiffness is desired and alower number or no horizontal layers 30 present when a lesser stiffnessis desired. When multiple horizontal layers are employed, horizontallymoving side cores can be used to form the portions of beam which are inbetween two horizontal layers, while the vertically moving cores for theother portions.

Turning now to FIGS. 4 and 5, a portion of the energy absorber 14 withtwo possible design configurations is illustrated. In the designillustrated in FIG. 4, vertical sidewalls 40 connect the energy absorberto the first wall 18 of the support structure 12. In FIG. 4, thesidewalls 40 of the energy absorber 14 do not vary in shape and/orthickness throughout the length of the energy absorber 14 which meansthat the energy absorber 14 can be extruded, thereby reducing toolingcosts for the manufacturer. FIG. 5 illustrates a similar embodimentexcept that sidewalls 40 contain corrugations 44. The corrugations 44can provide high stiffness to the energy absorber 14 at a minimalthickness. For example, thickness values as low as 1.2 mm could be usedif injection compression molding is employed, with thickness values aslow as 1.6 mm could be used for injection molding. In one embodiment,the minimal thickness can be 2.2 mm, e.g., for Xenoy® plastic resinwalls. The energy absorber 14 in FIG. 5 is also illustrated in FIG. 1attached to the first wall 18 of the support structure 12 and to thecrash cans 16.

The energy absorber 14 can be configured such that the energy absorber14 comprises an opening 36 in the space located between the front walland the sidewalls 40 (i.e., the energy absorber 14 is not enclosed onthe top and the bottom with respect to the y-axis). Similar to thesupport structure 12, such a design allows for vertical mold movement.In one embodiment, as illustrated in FIG. 1, the energy absorber 14 canextend across the length of the energy absorbing assembly in thedirection of the x-axis. The energy absorber 14 extends from a firstcrash can 16 across the support structure 12 to a second crash can 16(e.g., from an outer end of one crash can to the opposite end of theother crash can). In this embodiment, the energy absorber 14 is attacheda front face 50 of the crash can 16 as well as to the first wall 18 ofthe support structure. In another embodiment, the energy absorber 14 canextend across the length of the support structure 12 and not across thecrash cans 16.

Any structure can be used in the design for the sidewalls 40 of theenergy absorber 14 including any structure such as vertical, corrugated,quadratic curves, trapezoidal, hexagonal, pentagonal, octagonal,semi-circular, and combinations comprising at least one of the foregoingprovided that opening 36 is present. Any structure that allows verticalmold movement can be used as the sidewalls 40 illustrated in FIGS. 4 and5.

FIGS. 6 and 7 illustrate one embodiment of the crash can 16 component ofthe energy absorbing assembly 10. FIG. 6 displays the portion of thecrash can 16 that attaches to the vehicle components (not illustrated).Specifically, a back face 52 attaches the vehicle rails. Any type ofattachment mechanism can be utilized, including, but not limited to,bolt and nuts, screws, adhesives, and combinations comprising at leastone of the foregoing. FIG. 6 also illustrates hollow portion 58 locatedbehind back face 52 and surrounded by the ribs 54 and the vertical walls56. The crash can 16 also comprises side faces 60 which extend from thefront face 50 the back face 52. At least one of the side faces 60attaches to the fourth wall, fifth wall, and/or the ribs 24 of thesupport structure 12. The ribs 54 and vertical wall 56 provide stiffnessto the crash can 16 to aid it in absorbing energy upon an impact. Thehollow portion 58 of the crash can 16 is designed to absorb energy andcrush upon impact during low speed crashes (e.g., 15 km/hr).

The hollow portion 58 can comprise a conical structure such that thehollow portion comprises a smaller cross sectional area near the frontface 50 and a larger cross sectional area near the back face 52. Thehollow portion 58 of the crash can 16 can comprise any shape that willprovide the desired stiffness upon impact. For example, the hollowportion 58 of the crash cans 16 can comprise a shape such as conical,circular, square, rectangular, elliptical, trapezoidal, parabolic, andcombinations comprising at least one of the foregoing. The crash cans 16can comprise any shape that will provide the desired stiffness upon animpact. For example, the crash cans can comprise a shape such asconical, circular, square, rectangular, elliptical, trapezoidal, andcombinations comprising at least one of the foregoing. In oneembodiment, the front face 50 of the crash can 16 can attach to thesidewalls 40 of the energy absorber 14. In another embodiment, thesidewalls 40 of the energy absorber 14 do not extend to the crash cans16. In another embodiment, the crash cans 16 do not comprise the hollowportion 58 and instead comprise ribs 54 and vertical wall 56 in the areabetween the front face 50, back face 52 and side face 60.

In one embodiment, the crash cans 16 can be designed to not outwardlyextend past the first wall 18 of the support structure. The crash cans16 can be designed so that the front face 50 of the crash cans 16 arealigned with the first wall of the support structure 12. Such a designfacilitates an energy absorbing assembly 10 where the energy absorber 14extends across the entire length of the energy absorbing assembly 10.

FIGS. 8 and 9 illustrate a different embodiment of an energy absorbingassembly 70. FIG. 8 illustrates an integrated design of a supportstructure 72, energy absorber, 74, and crash cans 76. As can be seen inFIG. 8, the support structure comprises a rear portion 90 and sideportions 80. Ribs 82 protrude from the side portions 80 (e.g., extendoutward from side portions 80) and connect the support structure 72 tothe crash cans 76. As illustrated in FIG. 8, the rear portion 90 cancomprise a multi-layer structure to provide increased stiffness to thesupport structure 72. For example, the rear portion 90 can comprisegreater than or equal to 1 layer, specifically, greater than or equal to2 layers, more specifically greater than or equal to 3 layers, stillmore specifically, greater than or equal to 4 layers, and even morespecifically, greater than or equal to 5 layers. A plurality of crushlobes 78 form the energy absorber 74 and protrude outwardly from therear portion 90 of the support structure 72. The crush lobes 78 comprisea front wall 94 attached to sidewalls 96. The crush lobes generallycomprise four sidewalls 96. The energy absorber 74 can extend across thelength of the support structure 12 in one embodiment.

The crash cans 76 contain an attachment portion 86 with holes 88 (e.g.,for bolt, nuts, and/or screws) that can be used to attach the crash cans76 to the vehicular rails. The crash cans 76 contain a hollow portion 84which is designed to provide protection to a driver and/or occupant'slower leg during an impact. In one embodiment, the crash cans 76comprise a honeycomb structure 92 located in the hollow portion 84. Thehoneycomb structures can be formed, for example, using injection molding(one process for the molding of complete assembly) where the tool movesin the horizontal direction. The crash cans can be aligned with thefront wall 94 of the energy absorber 74 such that the crash cans 76 donot extend past the front face of the energy absorber. The crash cansare intended to deform and absorb energy upon impact thereby decreasingthe amount of energy that reaches the driver or occupant of the vehicle.The crash cans 76 absorb energy during an offset angled barrier impactof 15 kilometers per hour (kph) for RCAR impact requirements. The crashcans are able to satisfy the requirements of the test, i.e., the railupon which the crash cans are supported don't undergo permanent damage,there is minimum or no damage to the surrounding components, and theforce generated at the contact during the impact is less than 130kiloNewtons (kN). Conical crash cans 76 as illustrated in FIG. 8facilitate easy tooling of this component of the energy absorbingassembly 70. The convergent divergent conical walls with enough draft(e.g., greater than or equal to 4 degrees) facilitates core movementfront and rear. This is important because the axial movement of the toolis significantly high, varying from 150 mm to 200 mm. Although conicalcrash cans 76 are illustrated in FIG. 8, it is contemplated that anyshape crush box 76 could be utilized. For example, the crush box 76could comprise a shape such as conical, circular, square, rectangular,elliptical, trapezoidal, and combinations comprising at least one of theforegoing.

The structure of the crush lobes 78 is also not limited to thatillustrated in FIG. 8. The crush lobes can comprise any shape that willprovide the desired energy absorption characteristics. It can be of anyshape including conical, circular, parabolic, triangular, rectangular,trapezoidal, elliptical or combination of comprising at least one of theforegoing. FIG. 9 is a cross-section side view of the energy absorbingassembly of FIG. 8 taken along line A-A.

A method of making an energy absorbing assembly is also contemplated.For example, a support structure, energy absorber, and crash cans bemolded simultaneously to form a single piece integrated energy absorbingassembly, where single piece integrated assembly refers to the fact thatthe energy absorbing assembly components (i.e., support structure,energy absorber, and crash cans) cannot be separated from one anotherwithout damage to one of the components. Any method in which the supportstructure, energy absorber, and crash cans can be formed as anintegrated energy absorbing assembly can be used. For example, theenergy absorbing assembly can be molded by a process such as injectionmolding, extrusion, thermoforming, blow molding, and combinationscomprising at least one of the foregoing. When injection molding is usedto form the energy absorbing assembly 10, vertical mold movement can beused creating open spaces in the top and bottom of the support structureand in the top and bottom of the energy absorber.

The energy absorbing assembly is further illustrated by the followingnon-limiting examples.

EXAMPLES

The following examples are all simulations.

Simulated tests were conducted to validate the energy absorbing assemblyfor three major impacts: lower leg pedestrian impact, center pendulumimpact per ECE-42 protocols, and 10-degree RCAR impact. A genericvehicle with a curved polypropylene (PP) fascia, grille, a polycarbonate(PC) glass skin for the headlamp, a 25 pounds per square inch (psi)steel as the outer bonnet and a 2 mm thick steel spoiler as thelower-leg protector was chosen for study. The energy absorber materialused was Xenoy® plastic resin (PC/PBT blend) and the average thicknesswas maintained as 2.2 mm. The complete length of the assembly wasmaintained at 1,200 mm, width of 100 mm and a height of 100 mm.Pedestrian legform and the pendulum were allowed to hit this vehiclewith velocities as specified by the regulations mentioned above. Theenergy absorbing system weighed approximately 2.1 kilograms (kg), whichis lighter than designs comprising a metal support structure and/ormetal crash cans, where the assembly weighs approximately 3.2 kg. Theweight reduction is observed to be greater than 35%. The added advantageof a single piece assembly reduces the assembly cost by at least 50%because the costs associated with attaching the energy absorber over thesupport structure and the cost involved in attaching the supportstructure to the crash cans are completely eliminated with the presentdesign.

FIG. 10 displays a side view of the performance of the design of FIG. 1when the energy absorbing assembly is subjected to a lower legpedestrian impact. Lower leg pedestrian impact tests were conductedusing a vehicle platform with a 3 millimeter (mm) thick polypropylenefascia, a glass filled lower spoiler, and a stiff member on top the topto emulate the hood are used in conjunction with the single piece energyabsorbing assembly. Results are measured after no impact (0 milliseconds(ms)), after 8 ms, and after 16 ms. The legform is allowed to impact thevehicle assembly with a velocity of 40 km/hr and the acceleration,rotation, and shear at the knee location are measured to qualify thedamage. The measured values were observed to be well within the valuesprescribed by regulations (ACEA—phase II).

In another pedestrian lower leg impact test the support structureundergoes negligible deflection when it is subjected to lower legpedestrian impact. The displacement of the beam was observed to be lessthan 10 mm and was purely in the elastic regime; i.e., it did notundergo any permanent damage. The energy absorber walls buckle near themidpoint and absorb energy. Additionally, it is observed that the frontwalls of the energy absorber also absorb some energy by virtue of theirbending action, which contributes to having a highly efficient energyabsorbing assembly. The energy absorber crushes completely and absorbs asufficient amount of energy; i.e., the energy absorber absorbsapproximately 400 joules (J) of energy which is almost 50% of the totalimpact energy. The remaining energy is usually absorbed by the othervehicle components. The force levels are maintained steadily at 15kiloNewtons (kN) after the front portion of the energy absorber crushescompletely. The performance of the energy absorbing assembly isapproximately 126 G acceleration (wherein G acceleration is due togravity at the Earth's surface), less than 10 degrees of rotation, and ashear of less than 2.4 mm, with a packaging space of less than 50 mm,all of which meet the Phase II regulation requirements of less than 150G acceleration, less than 15 degrees rotation, and less than 6 mm ofshear by about 20%. In other words, the energy absorbing assembly hasabout a 20% safety margin over the Phase II regulation requirements.

FIGS. 10, 11, and 12 display graphical results of the acceleration,rotation, and shear testing of the energy absorbing assembly asdescribed above. These graphs represent the magnitude of theacceleration, rotation and the shear at the knee joint of the legformduring the impact. The maximum permissible values according to theregulation are 150 G, 15 degrees, and 6 mm, respectively. These resultsare very difficult to achieve using metallic support structures, asmetallic beams are very stiff for the low speed impact cases. As aresult, the efficiency of the energy absorbing assembly described hereinis very high, which can be observed in FIGS. 13 and 14. Efficiency isthe ratio of the area under the obtained force versus intrusion curveand the area of the rectangle with length and breadth as the intrusionand maximum force level. Therefore, for an energy absorber assembly tobe efficient, the area should be as high as possible and hence the dipin the force vs. intrusion curved after the first peak should beminimal, as shown in FIGS. 13 and 14. The complete energy absorbingassembly also performs well for center pendulum impact testing as perECE-42 regulatory requirements and RCAR impact.

FIG. 15 displays the results of the energy absorbing assembly for RCARimpact. The crash can crushes axially and absorbs up to 10 kiloJoules(kJ) of energy during the impact as illustrated in FIGS. 15 and 16. Theforce levels are maintained at around 120 kN during this testing. Thisis reaction force experienced during the impact. The force generatedduring the impact should not be high enough to cause a permanent damageto the rails on which the crash cans are mounted. The rail is observedto undergo no plastic deformation during the impact. However, if theenergy levels involved are lower, the crash cans can be designed to beless stiff.

The energy absorbing assemblies described herein comprise a single pieceintegrated assembly, which means that the individual components, e.g.,support structure, energy absorber, and crash cans, cannot be separatedfrom one another without causing damage to one of the other components.Each of the support structure, energy absorber, and crash can comprise athermoplastic material, thereby lowering the overall weight of theenergy absorbing assembly. The integrated design also decreasesprocessing and assembly time, and therefore also reduces the cost of theenergy absorbing assembly, while at the same time providing equivalentor greater energy absorbing characteristics.

In an embodiment, an energy absorbing assembly can comprise: a supportstructure having a first wall and an outer wall that extend in an xdirection from a first end to a second end; an energy absorber thatextends across the first wall of the support structure, the energyabsorber comprising a plurality of crushable members are configured tocrush and absorb energy upon impact, a first crash can; and a secondcrash can, wherein the first and second crash cans extend from the firstand second ends of the support structure. The energy absorbing assemblyis an in situ formed single element.

In one embodiment a vehicle comprises a body and rails and an energyabsorbing assembly. The energy absorbing assembly comprises a supportstructure having a first wall and an outer wall that extend in an xdirection from a first end to a second end; an energy absorber thatextends across the first wall of the support structure, the energyabsorber comprising a plurality of crushable members are configured tocrush and absorb energy upon impact, a first crash can; and a secondcrash can, wherein the first and second crash cans extend from the firstand second ends of the support structure and wherein the first andsecond crash cans attach to the rails without a bumper beam. The energyabsorbing assembly is an in situ formed single element.

In one embodiment, a method of making an energy absorbing assembly cancomprise: introducing molten thermoplastic material to a mold to, insitu form the energy absorbing assembly comprising a support structure,energy absorber, first crash can, and second crash can, wherein thesupport structure has a first wall and an outer wall having ends,wherein the first and second crash cans extend from the ends of thesupport structure, and the energy absorber extends across the first wallof the support structure; and removing the energy absorbing assemblyfrom the mold by moving the mold in a y direction.

In the various embodiments, (i) the support structure can compriseopenings in a y direction, and/or the energy absorber comprises openingsin the y direction, and/or the crash can comprises openings in the ydirection; and/or (ii) the energy absorber can extend in the x directionacross the first crash can, the support structure, and the second crashcan (e.g., can extend in the longitudinal direction across a front ofthe energy absorber assembly); and/or (iii) the support structure,energy absorber, and crash can each comprise a thermoplastic material;and/or (iv) the first and second crash cans comprise a back face with acavity open from the back face, wherein the cavity converges toward thefront face; and/or (v) the support structure has a structure stiffness,and wherein a stiffness of the first and second crash cans is greaterthan the structure stiffness, and wherein a stiffness of the energyabsorber is less than the structure stiffness; and/or (vi) the supportstructure has a sufficient stiffness to enable the energy absorber tocrush and absorb energy upon impact without a metal bumper beam; and/or(vii) the first and second crash cans comprise attachments sectionsconfigured for direct attachment to vehicle rails; and/or (viii) theouter wall of the support structure is a solid wall; and/or (ix) theenergy absorber has a solid wall outer wall located opposite the supportstructure outer wall; (x) the front face of the first and second crashcan is a solid wall; and/or (xi) the first and second crash cans do notextend past the front wall of the energy absorber; and/or (xii) theenergy absorbing assembly has cavities that are open in the y directionon both sides of the energy absorbing assembly; and/or (xiii) the energyabsorber and the support structure have solid outer walls that extend inthe x and y directions.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other (e.g., ranges of“up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, isinclusive of the endpoints and all intermediate values of the ranges of“5 wt. % to 25 wt. %,” etc.). “Combination” is inclusive of blends,mixtures, alloys, reaction products, and the like. Furthermore, theterms “first,” “second,” and the like, herein do not denote any order,quantity, or importance, but rather are used to d one element fromanother. The terms “a” and “an” and “the” herein do not denote alimitation of quantity, and are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The suffix “(s)” as used herein is intended toinclude both the singular and the plural of the term that it modifies,thereby including one or more of that term (e.g., the film(s) includesone or more films). Reference throughout the specification to “oneembodiment”, “another embodiment”, “an embodiment”, and so forth, meansthat a particular element (e.g., feature, structure, and/orcharacteristic) described in connection with the embodiment is includedin at least one embodiment described herein, and may or may not bepresent in other embodiments. In addition, it is to be understood thatthe described elements may be combined in any suitable manner in thevarious embodiments.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or may be presently unforeseen may arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they may be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

1. An energy absorbing assembly, comprising: a support structure havinga first wall and an outer wall that extend in an x direction from afirst end to a second end; energy absorber that extends across the firstwall of the support structure, the energy absorber comprising aplurality of crushable members are configured to crush and absorb energyupon impact, first crash can; and second crash can, wherein the firstand second crash cans extend from the first and second ends of thesupport structure; wherein the energy absorbing assembly is an in situformed single element.
 2. The energy absorbing assembly of claim 1,wherein the support structure comprises openings in a y direction,and/or the energy absorber comprises openings in the y direction, and/orthe crash can comprises openings in the y direction.
 3. The energyabsorbing assembly of claim 2, wherein the energy absorber extends inthe x direction across the first crash can, the support structure, andthe second crash can.
 4. The energy absorbing assembly of claim 2,wherein the support structure, energy absorber, and crash can eachcomprise a thermoplastic material.
 5. The energy absorbing assembly ofclaim 1, wherein the first and second crash cans comprise a back facewith a cavity open from the back face, wherein the cavity convergestoward a front face.
 6. The energy absorbing assembly of claim 1,wherein the support structure has a structure stiffness, and wherein astiffness of the first and second crash cans is greater than thestructure stiffness, and wherein a stiffness of the energy absorber isless than the structure stiffness.
 7. The energy absorbing assembly ofclaim 1, wherein the support structure has a sufficient stiffness toenable the energy absorber to crush and absorb energy upon impactwithout a metal bumper beam.
 8. The energy absorbing assembly of claim1, wherein the first and second crash cans comprise attachments sectionsconfigured for direct attachment to vehicle rails.
 9. The energyabsorbing assembly of claim 1, wherein the outer wall of the supportstructure is a solid wall.
 10. The energy absorbing assembly of claim 1,wherein the energy absorber has a solid wall outer wall located oppositethe support structure outer wall.
 11. The energy absorbing assembly ofclaim 1, wherein a front face of the first and second crash can is asolid wall.
 12. The energy absorbing assembly of claim 1, wherein thefirst and second crash cans do not extend past the front wall of theenergy absorber.
 13. A vehicle comprising: a body having a frame andrails; an energy absorber assembly comprising a support structure havinga first wall and an outer wall that extend in an x direction from afirst end to a second end; energy absorber that extends across the firstwall of the support structure, the energy absorber comprising aplurality of crushable members are configured to crush and absorb energyupon impact, first crash can; and second crash can, wherein the firstand second crash cans extend from the first and second ends of thesupport structure, and wherein the first and second crash cans attach tothe rails without a bumper beam; wherein the energy absorbing assemblyis an in situ formed single element.
 14. A method of making an energyabsorbing assembly, comprising: introducing molten thermoplasticmaterial to a mold to, in situ form the energy absorbing assemblycomprising a support structure, energy absorber, first crash can, andsecond crash can, wherein the support structure has a first wall and anouter wall having ends, wherein the first and second crash cans extendfrom the ends of the support structure, and the energy absorber extendsacross the first wall of the support structure; and removing the energyabsorbing assembly from the mold by moving the mold in a y direction.15. The method of claim 14, wherein the energy absorbing assembly hasopen cavities in the y direction on both sides of the energy absorbingassembly.
 16. The method of claim 14, wherein the energy absorber andthe support structure have solid outer walls that extend in the x and ydirections.
 17. The method of claim 14, wherein the energy absorberfurther extends across the first and second crash cans.